This invention relates to novel gels, particularly hydrogels, having flavors or fragrances entrapped therein.
Hydroxy (lower alkyl) acrylate and methacrylate polymers (some of which are available under the trademark HYDRON) are known to be excellent slow-release vehicles and this use is a subject of many patents and patent applications. Both the crosslinked and soluble polymers of this type have this property and have been shown to slowly release biologically active compounds, flavors, fragrances, etc. In all the published (and patented) uses the ratio of the active substance to polymer cannot be much higher than 1:1 and is usually less, normally being less than 30% in the case of flavors and fragrances, for example, because otherwise the cohesiveness of the polymeric matrix is lost and as a result of this it is impossible to obtain continuous films from the soluble polymer or definite, shape retaining objects from the crosslinked polymers. The amount of crosslinking agent is usually kept low, between 0.05 to 2.0 weight %. Only for some special uses higher amounts of the crosslinking agent were proposed, usually between 10 to 15 weight % U.S. Pat. Nos. 3,574,286, 3,618,231, and 3,761,286, the highest being 20 weight % in U.S. Pat. No. 3,470,883. Other patents of interest in this connection are U.S. Pat. Nos. 2,976,576; 3,699,089; 3,551,556; 3,689,634; 3,697,643; and U.S. Pat. No. Re. 27,401.
The use of more than 20% of crosslinking agent is shown in U.S. Pat. Nos. 3,503,942; 3,792,028; and 3,728,315. However, none of these latter patents are concerned with the use of polymers for loading fragrances and flavorings.
Prior art hydroxyalkyl acrylate and methacrylate polymers which have been loaded with fragrances and flavorings as indicated supra generally had low amounts of crosslinking agent and generally low fragrance loading (up to 30% and usually much less). These polymers were generally meant to be pulverized. High fragrance loading under these conditions is impractical, because if the mixture polymerizes at all, the gel is not self-supporting but mushy, crumbling or flowing. In water the product usually does not have any cohesion altogether.
Typical prior art disclosed polymeric products or articles made from, for example, HEMA (hydroxyethyl methacrylate), up to 5 weight % diester (based on the total weight of monomers), and up to 25 weight % of fragrances, essences, flavors, and the like ("FF" for cconvenience), based on the total weight of the formulation. Approximately 25 weight % of FF represents the highest loading in the formulation since as stated greater amounts result in a product or article which loses its, self-supporting or self-retaining properties. Thus, the prior art products were useful in the form of powders or coatings, etc., in which, for example, moisture activated the FF and thereby caused its slow release to the environment.
If one desired to manufacture a prior art product which would self-activate the slow release of the FF, one would incorporate into the polymerizable formulation a solvent, e.g., 20 weight % (based on the total weight of the formulation).
However, in the case such a solvent were added the resulting product is soft, crumbles under mild hand pressure, is not truly self-supporting, and is opaque whereas the commercial trade desires clear, hard, self-supporting, slow-release articles.